Amplifying-micbophone beceiveb



July 14, 192s.v

cfs. wlLLrAMs" murrine lrcnornoun nncar'vzn 1 Filed I mr'cn fa. 1923*`Patented July 14, 1925.

UNITED .STATES 1,545,718 PATENT OFFICE.

CHARLES E. WILLIAMS, 0F CHICAGO, ILLINOIS.

A.'MIILIIFYING-IMICROIHONEl RECEIVER.

Application med umh 5, 192s. ser 1a1no. e22,sas.

ITo all whom it may concern. l

Be it known that I, CHARLES E. WILLIAMS, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a new and useful Improvement in an Amplifying-MicrophoneReceiver, of which the following is a specification.

My present invention relates to the provision of an amplifyingmicrophone receiver, and has special reference to the provision of anear-piece or receiver for use in apparatus for assisting persons withimpaired hearing, although the principles herein disclosed may beapplied to any telephone receiver or instrumentalities for converting afluctuating electric current into sound in cases where it isadvantageous to increase the audibility of the signals.

The object of my presentinvention is the provision of instrumentalitieswhereby the vibrations of a diaphragm caused by a liuctuating electriccurrent are employed to cause amplifying of the vibrations of thediaphragm. I prefer to carry'out the beforementionedobject by means ofthe structure illustrated in the accompanying drawings,

in whiching.

Fig. 4 is av diagram of the circuitsemployed.

The mechanism consists of a cu' -shaped or cylindrical casing 5, the lipen thereof is exteriorl threaded to receive an interiorly threade flangeof a centrall apertured cap or closure 6. The flange o the cap orclosure is thickened at its base to provide the annular shoulder-,7which comes opposite the ed of casing 5,` and between which edge an saidshoulder is interposed and secured a diaphragm 8. Upon the'interior faceof the bottom of casing 5 is secured a plate 9 to -.diametricallyopposite portions4 of which are secured brackets 10 of magneticallyermeable material, the outer portions of w ich latter are extendedtoward each other substantially in .alinement and terminate in lateralpro]ections 11 extending `17 with the rst mentioned diaphragm 8. I

ployed for securing rod 17 to the respective 'i in parallel relationtoward diaphragm 8.

Vbore 12, is an annulus 13 formed of aluminum or other suitable metal.The outer part of the interior of the annulus is cut-away and interiorlythreaded to receive an exteriorly threaded block of closure 14 of fibreor othersuitable insulating material, the `inner surface vwhereof iscut-away to provide a cylindrical cavity 15. Between the portion of theinner face of block 14 and cavlty 15 and the shoulder formed by theenlargement of the central opening in annulus 13 is secured a diaphragm16 whichV is connected by the ro'd have shown nuts 18 as means forconnecting 80 the ends of rod 17 with the respective diaphragms, butthis connection maybe satisfactorily attained by the use of cement, orin any desired manner. y

In cavity 15 of block 14 is placed the usual carbon electrode of amicrophone transmitter which consists of a disk 19 of compressed carbonhaving a plurality of conical cavities 2O on` the face thereof which isadjacent diaphragm 16. These cavities are filled with the usualcarbongranules 21 which act as the con'ductor of the current between thediaphragm and carbon block 19, and the variation of the com ression ofwhich, resulting from the vi rations of the diaphragm 16,- changes theconductivity of the granules and causes the modification of the currenttocorrespond to the liuctuations of said diaphragm. When nuts 18 areemdiaphragms, a centrally located recess 19 is provided in the upperface of block 19 to accommodate the lower end of rod 17 and the nutattached thereto.

As seen in Fig. 4 of the drawings, the current originatinv in battery Cis modified in the usual way y the sounds received in transmitter D andpasses through conductors E and coils B, B, which, as usual, causes thefluctuation of diaphragm 16. A steady current is meanwhile passing frombattery F, coils A, A, diaphragm 16, granules 20 and carbon block orelectrode 15. Thiscurrent is normally steady and pro'duces an even pull.on diaphragm-16,'but when diaphragm Cil 16 is set in vibration throughthe'action of transmitter D this'vibration is .transmitted through rod17 to'diaphragm 16 and the granules 21 are subject `tointermittentcomv'pression correspondin 4to the impulses received attransmitter thereby causing the current flowing from battery F throughcoilsv connection therebetween, an electro-magnet -1n co-operatlverelatlon wlth one of said diaphragms, a plurality of conductor coils 1nco-operative relation wlth said magnet, a pressure variable reslstance1n co-o rative .5 relation with the other of said diap ragms,

a signaling circuit including Aa coil of said magnet; and an auxiliarycircuit including the'other ofs'aid diaphragms, said pressurevariableresistance and another o-said coils.

2. An instrument for converting a flucreceiver comprlsmg a pair ofdiaphragms, a mechanical tuating current into mechanical vibrationscomprising a pair of diaphragms, a mechanical connection therebetween,conductor coils in magnetic ation with one of said diaphragms, apressure variable resistance in co-operative relation with the other ofsaid diaphragms, a signaling vcircuit including certain of said coils,and anl auxiliary circuit including the other of said -diaphra s, saidpressure variable resistance an certain other of said coils.

3. An amplifying telephone receiver coma plurality of re .prising a pairof diaphragms disposed in opposing parallel relation, a. rod connectingsaid diaphragms, an electro-magnet in cooperative relation withlone ofsaid diaphragms, a plurality of conductor coils in magnetic relationwith said magnet, a presf sure variable resistance in cb-operativerelation with the other of said diaphragms,

a signaling circuit including certain of said coils, and a secondcircuit including the other of said coils, said pressure variableresistance and the diaphragm with which it is in co-operative relation.

Signed at Chicago, county of Cock and State of Illinois, this 27th dayof February 1923. v

p 'CHARLES E. WILLIAMS.

Witnesses: I

' R. M. Bm.,

Bano'. T. 'Roonnonsn

